The existing classes already look really fun! Classes with pets, summons, etc. as teased in some concept art might be fun to look into, after the first 'tank' class (:

I love lore, but think it should be more organic, things people can pick up during normal gameplay without having to sit through hours of cutscenes or dialogue. Lore compendiums like in Mass Effect menu or the books in Elder Scrolls, extra lore for avid readers, are a great medium.

I would love to hear their thoughts about situational music, eg. combat music VS "ambient" zone music, and their preferences. WRT Sound effects design, I would love to hear how any sounds are selected/recorded for skills & other abilities.

I agree with this exactly!
I also enjoy generic support classes that are primarily about providing buffs to other players, shaman is a good example, whether it's "dps" or "heal"; but things like boosting speed of other players can be really good in a pinch.